Vanessa was assigned problems 43 through 82 for homework last week. If Vanessa did all of the problems she was assigned, how many problems did she do?
Explanation: Instead of counting problems 43 through 82, we can subtract 42 from each number so we instead consider problems 1 through 40. We see that Vanessa did 40 problems. Notice that she did 40 and not 39 problems.